We have added a new function to the MOPAC program package by employing the methods of corresponding orbital transformation and generalized density matrix and developed a new program called MOPAC- ET, which can deal with the electron transfer reactions. We have also calculated a molecule with spiro π-electronic structure by use of this method and obtained its potential energy surface, exothermicity ΔE, reorganization energy λ and electron transfer matrix elements V~A~B. The results indicate that V~A~B and λ are not obviously affected by the outer electric field while the ΔE is directly proportional to it. The calculated results of title compound 1 were also compared with that from ab initio method. It was found that our results are consistent with that calculated by ab initio method. This approved the reliability of the program MOPAC-ET. In addition to this, the program has advantages of faster speed and less time consuming over the ab initio methods, thereby can be used to simulate the electron transfer for the large systems such as biological macromolecules.

Key words: ELECTRON TRANSFER REACTION, ELECTRON MATRIX ELEMENT, AM1 METHOD, DIPOLE MOMENTS, TOTAL ENERGY, SPIRO COMPOUNDS